# [Tex/LaTex] How to left-align using eqnarray in latex

equationshorizontal alignment

Now, first of all let me get something clear: I do not ask for any reasons why align is btter than eqnarray. All I ask is a simple way to make this work, using eqnarray (It's obviously possible, but I'm not sure how).

\begin{eqnarray}~\label{eqn07}
\begin{tabular}{llll}
$\Psi_{1}(x,\lambda)$ & = & & $U(x,\lambda)e_{1}$ \cr
&   & & \cr
\end {tabular}
\end {eqnarray}


Yet after compiling it, I get the equation centered, instead of left-aligned. I've tried to insert \left{ ... \right} , but it wouldn't even build, and I just had many errors popping up. Could someone tell me a simple way to do so, wihout using \begin{align}. I do want to use \begin{eqnarray} (I've got my own reasons why).

You should add the fleqn option to your document class. Regardless, the following is the correct way of using eqnarray:

\documentclass[fleqn]{article}
\begin{document}
\begin{eqnarray}
\Psi_{1}(x,\lambda) & = & U(x,\lambda)e_{1}\label{eqn07}
\end{eqnarray}
\end{document}


You'll notice that the equation is left-aligned, although not flush with the left margin. To achieve this, add \setlength{\mathindent}{0pt} to the document preamble as well.

Note that you don't need eqnarray for a single equation. For this, the equation environment is sufficient. However, since the spacing of eqnarray is inferior to the regular math spacing, it might be better for consistency.